1. Field
The disclosed concept pertains generally to electrical switching apparatus and, more particularly, to relays, such as, for example, aircraft relays.
2. Background Information
A conventional electrical relay includes a movable contact, which makes or breaks a conductive path between main terminals. Control terminals electrically connect to an actuator coil having a number of actuator coil windings. On many relays, the actuator coil has two separate windings or a partitioned winding used to actuate closure of separable main contacts, and to hold the separable main contacts together in a relay closed or on state. The need for the two coil windings is the result of the desire to minimize the amount of electrical coil power needed to maintain the relay in the closed state.
A typical normally open relay has a spring on its armature mechanism that holds the separable main contacts open. In order to initiate movement of the armature mechanism for closure, a relatively large magnetic field is generated to provide sufficient force to overcome the inertia of the armature mechanism and, also, to build up enough flux in the open air gap of a solenoid to create the desired closing force. During closure motion of the armature mechanism, both coil windings are energized to produce a sufficient magnetic field. After the main contacts close, the reluctance of the magnetic path in the solenoid is relatively small, and a relatively smaller coil current is needed to sustain the force needed to hold the main contacts together. At this point, an “economizer” or “cut-throat” circuit can be employed to de-energize one of the two coil windings to conserve power and to minimize heating in the solenoid.
There is room for improvement in electrical switching apparatus, such as relays.